This study aimed to investigate the effect of reducing the amount of organic waste on the weight of cats in Tehran. The weight of 4192 cats was measured from spring 2016 to the end of winter 2020. They were classified into 6 age groups, 2 gender groups, and 13 geographical areas. Their weight was measured for 48 months (16 seasons). The statistical parameters analysis showed no weight loss in 2017, but since 2018, cats have been losing weight every year. They had lost about 178g of their weight in 2018. The sharpest annual decrease was observed in 2019 when about 301g of weight loss was recorded. In the winter of 2020, 115g of weight loss took place. In the spring of 2017, no weight change was observed, but in the spring of 2018, the cats lost 155g of their weight. Their weight loss intensified in the spring of 2019 and about 299g of weight loss was observed. In the summer of 2017, as in the spring of the same year, no weight loss was recorded, but for the summer of 2018, the weight loss was evident and about 205g of the weight of the cats had been reduced. The weight loss in the summer of 2019 not only continued but intensified and about 304g of weight loss was recorded for cats. Weight change was not observed in the fall of 2017 as in the spring and summer of the same year. In the fall of 2018, weight loss was recorded for cats. They had lost about 324g of their weight in the fall of 2018. Also, they experienced a weight loss of about 218g in the fall of 2019. During the spring, summer, and autumn of 2017, no weight loss was observed in the cats for the winter of 2018, but in the winter of 2019, the cats faced the most severe weight loss (seasonally). They lost about 401g of weight in the winter of 2019. Of course, in the winter of 2020, about 186g of weight loss was observed in cats. The results showed that female cats did not lose weight in 2017 but experienced weight loss in 2018 with a weight loss of 181g. The weight loss of females intensified in 2019 and 294g of weight loss was recorded. Female cats lost 186g of their weight in the winter of 2020. Male cats did not lose weight like female cats in 2017. But in 2018, a weight loss of 166g was observed in male cats. The weight loss of male cats continued in 2019 and 311g of weight loss was recorded for them. However, in 2020, unlike females, weight loss was not observed in male cats. It can be said that both sexes lost more weight in the winter of 2019 than in other seasons. In 2017, weight loss was observed only for the region of 10, and in the same year, weight gain was recorded for the region of 15. But in 2018, except for regions 3, 4, 15, and 19, weight loss was observed in other regions. In 2019, the weight loss of cats spread and weight loss was observed in all regions except the region of 12. In winter 2020, weight loss was recorded only in the region of 4. In the end, it can be concluded that the weight of cats has decreased since the spring of 2018 because the beginning of the decrease in the amount of organic waste has been recorded since the winter of 2018. So, there is a direct relationship between the weight of cats and the amount of organic waste (access to food). The amount of garbage has been decreasing since the winter of 2018, and the average weight of cats has also been decreasing since the spring of 2018 due to the decrease in access to food.